Median survival of high-grade gliomas remains less than a year, despite multi-modality treatment. Cure is considered anecdotal. These tumors usually have extended beyond the limits of a complete surgical resection, and the dose of conventional external beam radiotherapy has been limited by surrounding normal brain tolerance. We believe that we can achieve a higher radiation dose to the tumor by placing radioactive seeds of Iodine-125 directly into the tumor bed, with a sharp fall-off of radiation to the surrounding normal brain. Hopefully this will achieve a much better therapeutic ratio, especially when delivered at low dose rates.